On Thursday the firm was acquitted of a corporate manslaughter charge on the direction of the judge Mr Justice Mackay, who also cleared five rail bosses of the same charge.

The five members of management and their employer Network Rail, formerly known as Railtrack, still face health and safety charges.

The London to Leeds train derailed at 115mph near Hatfield on October 17, 2000, after a stretch of defective track shattered.

Crash victims Steve Arthur, 46, from Pease Pottage, West Sussex; Peter Monkhouse, 50, of Headingley, Leeds; Leslie Gray, 43, of Tuxford, Nottingham; and Robert James Alcorn, 37, of Auckland, New Zealand; were all on coach G of the 12.10 GNER East Coast express train.

Ronald Thwaites QC said Balfour Beatty admitted that between December 14, 1999 and October 18, 2000, the company failed to conduct the safe maintenance of the line to ensure passengers were not exposed to health and safety risks.

Mr Thwaites said there was no one single cause of the derailment.

He said the breaches were significant when aggregated with failures on the part of others.

The company accepted that it failed to ensure visual inspections of the track by its Hitchin office were carried out in the appropriate location.

It admitted they did not act on reports of track defects at the crash site, ensure by audit that the reports were acted upon, or examine the reports during a backlog recovery plan after June 2000.

Mr Thwaites said that Balfour Beatty did not fail to comply with Railtrack standards and claimed the crash might not have happened if there was an 'adequate grinding regime'.

Mr Justice Mackay said he would sentence the company after another hearing as the company did not accept all the allegations outlined by the prosecution.

Jurors have heard five months of evidence about the problems leading up to the crash.

Cracks were discovered at least 21 months before the crash and listed for urgent replacement in February 2000.

But the new rail was never installed by a sub-contractor and remained lying by the side of the track after the disaster.

Railtrack managers Alistair Cook, 51, Sean Fugill, 51, and Keith Lea, 55, and Balfour Beatty managers Anthony Walker, 47, and Nicholas Jeffries, 55, deny the health and safety offences.

Railtrack also deny a health and safety charge.

The trial continues.